Calculating friction

  • Thread starter bobsmith76
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  • #1
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Homework Statement



A sled weighing 70kg, going at 14 m/s, slides down a ramp 3 m high. It's final velocity is 15.6 m/s. How much energy was lost due to friction?


Homework Equations



.5mvi2 + mgh = .5mvf2 + x

where x = joules of energy for friction

The Attempt at a Solution



step 1 .5(70)(142+70(9.8)(3) = .5(70)(15.62 + x

step 2 6860 + 2058 = 8570 + x

step 3 6860 + 2058 - 8570 = x

step 4 401 = x

The books says the answer is 74
 

Answers and Replies

  • #2
Doc Al
Mentor
45,093
1,397
I'd say that you were correct. (8570 is a typo, though.)
 

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